Vehicle driving apparatus

ABSTRACT

In a vehicle in which side covers are disposed at the underfloor sides of a vehicle body, a totally enclosed main motor is disposed outside a frame of a chassis. The totally enclosed main motor includes an outside air ventilating flue through which the outside air is suctioned from a suction inlet, circulated and then exhausted from an exhaust outlet. The totally enclosed main motor uses the outside air ventilating flue to release heat generated internally to the outside. One end of a ventilating duct is connected to the suction inlet and the other end opens toward the outside of the vehicle at the side covers. With this, it is possible to supply the outside air from the outside of the vehicle thereby enhancing the cooling efficiency. Moreover, it is possible to use the totally enclosed main motor of a high capacity by disposing outside the frame of the chassis.

TECHNICAL FIELD

The present invention relates to a vehicle driving apparatus that drivesa vehicle of an electric train or the like, and particularly relates toa vehicle driving apparatus that uses a totally enclosed electric motor.

BACKGROUND ART

A vehicle driving apparatus for driving a vehicle of an electric trainor the like uses, as a driving source, an electric motor that isdisposed under the floor of the vehicle body and runs the vehicle bytransferring the torque of the electric motor to the wheels of thevehicle via gear devices and axles disposed on a chassis. With theincrease in the running speed of vehicles, there is a demand for furtherreduction in the size and weight as well as further increase in thecapacity of electric motors.

Conventionally, as an electric motor of this kind, an open type electricmotor is disposed in which outside air is drawn in and used as coolingwind. Since outside air containing dust is drawn in an open typeelectric motor, it is necessary to perform maintenance tasks, such asreplacement of filters for preventing taint damage to the electric motorand disassembling of the electric motor for periodical cleaning ofinternal parts, specific to the open type structure. Meanwhile, with theaim of enhancing comfort, there is a demand for noise reduction in thevehicular environment; and noise reduction of electric motors is anissue of particular concern among the issues regarding open typeelectric motors.

Thus, in response to the pursuit of less maintenance and the measuresfor reducing internal and external vehicular noise, totally enclosedelectric motors have been developed. Because of its structure, the heatreleasing capacity of a totally enclosed electric motor is substantiallylow as compared to an open type electric motor. Therefore, it isnecessary to enhance the cooling efficiency. As an example of a coolingsystem for a totally enclosed electric motor, an outside air ventilatingflue is disposed in the electric motor in isolation with the inside ofthe electric motor. Then, the outside air is ventilated through theoutside air ventilating flue. Because of that, heat exchange occursbetween the sealed air circulating inside the electric motor and theoutside air flowing through the outside air ventilating flue. As aresult, the heat generated inside the electric motor is released to theoutside (e.g., see Patent Literature 1).

Patent Literature 1: Japanese Patent Application Laid-open No.2004-194407

Patent Literature 1: Japanese Patent Application Laid-open No.S58-129194

DISCLOSURE OF INVENTION Problem to be Solved by the Invention

However, following problems are found in a vehicle driving apparatusthat uses a conventional totally enclosed electric motor.

In recent times, from the perspective of external aesthetics or with theaim of reducing travel resistance of train vehicles, it is commonpractice to dispose side covers at the underfloor sides of a vehiclebody. If a totally enclosed electric motor is disposed under the floorof a vehicle having the side covers, then the air that has itstemperature increased due to the heat release of the electric motorstagnates in the region surrounded by the side covers. Consequently, thehigh temperature air gets re-guided to the outside air ventilating flueas the cooling wind. This causes a substantial degradation in thecooling efficiency of the electric motor. As described above, thecooling efficiency in a totally enclosed electric motor is originallylow as compared to an open type structure. Besides, attachment of theside covers to the vehicle causes further degradation in the coolingefficiency.

Conventionally, a vehicle driving electric motor is attached to achassis that is disposed in the bottom part of a vehicle body. Becauseof that, the dimensions of the electric motor are constrained by therange of a standard rail width. This forces restriction on increasingthe capacity of the electric motor. Particularly, in the case of atotally enclosed electric motor, it is necessary to additionally providea cooling mechanism to enhance the cooling capacity. As a result, thesize of a totally enclosed electric motor increases as compared to anopen type electric motor capable of giving identical performance. Thismakes it difficult to install a high-capacity totally enclosed electricmotor in a vehicle. Thus, if the required capacity is high, thensometimes the task of installing a totally enclosed electric motor on achassis itself is not viable.

The present invention has been made to solve the above problems in theconventional technology and it is an object of the present invention toprovide a vehicle driving apparatus that enables achieving enhancementin the cooling efficiency and enables installation of a high-capacitytotally enclosed electric motor.

Means for Solving Problem

In order to solve the above mentioned problem and achieve the object, avehicle driving apparatus according to the present invention that isdisposed in a vehicle having a side cover at an underfloor side of avehicle body and that runs the vehicle, with an electric motor as apower source, by rotatively driving an axle disposed on a chassis of thevehicle and a wheel fixed to the axle, the vehicle driving apparatusincludes a totally enclosed electric motor that is disposed outside aframe of the chassis placed under a floor of the vehicle body, thatincludes an outside air ventilating flue through which outside air issuctioned from a suction inlet, circulated and exhausted from an exhaustoutlet, and that uses the outside air ventilating flue to release heatgenerated internally to outside; a shaft that transmits a rotary driveforce of the totally enclosed electric motor to the axle; and aventilating duct that connects between the suction inlet and an openingformed on the side cover.

EFFECT OF THE INVENTION

According to an aspect of the present invention, a ventilating duct isdisposed to connect a suction inlet of a totally enclosed electric motorto an opening formed on a side cover. Therefore, it becomes possible tosupply the outside air from the outside of the vehicle as cooling windto the totally enclosed electric motor. This eliminates the possibilityof a conventional problem in which high temperature air affected by theexhaust heat around the totally enclosed electric motor is supplied. Asa result, the cooling efficiency of the totally enclosed electric motorcan be constantly maintained at a high level.

According to another aspect of the present invention, the cooling windfrom the outside of the vehicle is supplied via the ventilating ductwith the use of an air suction feature of an outside air ventilatingflue that is disposed in the totally enclosed electric motor. Thiseliminates the need of newly disposing a device for producing a forceddraft. Moreover, unlike in the conventional technology, the vehiclerunning wind generated when the vehicle is running is not used. Thus,even if it is not possible to obtain sufficient vehicle running windwhen the vehicle slows down or when the electric motor is operatingafter the vehicle comes to a halt, it is still possible to maintain ahigh cooling efficiency.

According to still another aspect of the present invention, the totallyenclosed electric motor is disposed outside the frame of a chassis. Thiseliminates the dimensional constraints regulated by the chassis whileinstalling the totally enclosed electric motor. Thus, it becomespossible to dispose a high-capacity the totally enclosed electric motor.That is, by loading the totally enclosed electric motor to the vehiclebody portion other than the chassis, it becomes possible to securesufficient space and thus increase the capacity of the totally enclosedelectric motor.

Moreover, since the totally enclosed electric motor is disposed outsidethe frame of the chassis, a shaft is disposed to connect the totallyenclosed electric motor to an axle. In addition to its primary functionof transmitting the rotary drive force of the totally enclosed electricmotor to the axle, the shaft has good heat conductivity because of itsmetallic material. Thus, by helping the heat to release from the totallyenclosed electric motor, the shaft contributes to the cooling effect.This enables achieving further enhancement in the cooling efficiency ofthe totally enclosed electric motor.

In this way, according to an aspect of the present invention, inaddition to achieving the conventional advantages, such as lessmaintenance and low vehicular noise, of a totally enclosed electricmotor; it is possible to provide a vehicle driving apparatus thatincludes a totally enclosed electric motor that has a high capacity aswell as enhanced cooling efficiency.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a schematic side view illustrating a configuration of avehicle driving apparatus according to a first embodiment.

FIG. 2 is a schematic plan view illustrating the configuration of thevehicle driving apparatus according to the first embodiment when thebottom part of the corresponding vehicle is viewed from below.

FIG. 3 is a detail view illustrating a joint portion between an axle anda shaft illustrated in FIG. 1.

FIG. 4 is a cross-sectional view illustrating an exemplary configurationof a totally enclosed main motor according to the first embodiment.

FIG. 5 is a schematic plan view illustrating a configuration of thevehicle driving apparatus according to a second embodiment when thebottom part of the corresponding vehicle is viewed from below.

FIG. 6 is a schematic plan view illustrating an exemplary modificationof the configuration of the vehicle driving apparatus according to athird embodiment when the bottom part of the corresponding vehicle isviewed from below.

FIG. 7 is a schematic plan view illustrating a configuration of thevehicle driving apparatus according to the third embodiment when thebottom part of the corresponding vehicle is viewed from below.

FIG. 8 is a schematic side view illustrating a configuration of avehicle driving apparatus that does not include a ventilating duct.

FIG. 9 is a schematic plan view illustrating the configuration of thevehicle driving apparatus illustrated in FIG. 8 when the bottom part ofthe corresponding vehicle is viewed from below.

FIG. 10 is a plan view illustrating a configuration of a conventionalvehicle driving apparatus.

EXPLANATIONS OF LETTERS OR NUMERALS

1 vehicle body

2 chassis

3 a, 3 b axle

4 a, 4 b wheel

5 totally enclosed main motor

6 shaft

8 side cover

9 ventilating duct

10, 18 a, 18 b, 31 opening

11 connecting portion

12 joint portion

13, 14 gear

17, 20 a, 20 b dust collecting filter

19 ventilating duct

30 ventilating duct

51 stator

52 stator winding

53 rotor

54 inside air ventilating flue

55 outside air ventilating flue

56 inner fan

57 outer fan

58 suction inlet

59 exhaust outlet

101 a, 101 b main motor

102 a, 102 b gear device

103 a, 103 b gear-type flexible coupling

104 chassis frame

105 a, 105 b axle

106 wheel

BEST MODE(S) FOR CARRYING OUT THE INVENTION

Exemplary embodiments for a vehicle driving apparatus according to thepresent invention will be described below in detail with reference tothe accompanying drawings. The present invention is not limited to theembodiments described below.

First Embodiment

FIG. 1 is a schematic side view illustrating a configuration of avehicle driving apparatus according to the present embodiment. FIG. 2 isa schematic plan view illustrating the configuration of the vehicledriving apparatus according to the present embodiment when the bottompart of the corresponding vehicle is viewed from below. The vehicledriving apparatus according to the present embodiment is disposed in atrain vehicle or the like, and runs the corresponding vehicle byconverting electric power into torque with the use of an electric motorof a totally enclosed type electric motor (hereinafter referred to as atotally enclosed electric motor).

In the bottom part of a vehicle body 1, which is the main part of thetrain vehicle, are disposed chassis 2. On each chassis 2 are disposedaxles 3 a and 3 b. A wheel 4 a is impactedly fixed to each end of theaxle 3 a, while a wheel 4 b is impactedly fixed to each end of the axle3 b. In the example illustrated in FIG. 1, two chassis 2 are disposed ina single vehicle and each chassis 2 has two axles. However, in FIG. 2,the chassis 2 are omitted for simplicity. Moreover, the axles and thewheels disposed on only one chassis are illustrated in FIG. 2. That is,the axles and the wheels disposed on the other chassis are omitted forsimplicity.

From the perspective of aesthetics or with the aim of protecting theequipments and reducing travel resistance, side covers 8 are disposed atthe underfloor sides of the vehicle body 1. The side covers 8 are, forexample, skirts or the like and are disposed at both the underfloorsides of the vehicle body 1.

Outside the frame of the chassis 2, which are placed in the bottom partof the vehicle body 1, is disposed a totally enclosed main motor 5. Inthe present embodiment, disposing the totally enclosed main motor 5outside the frame of the chassis 2 allows a higher degree of freedomwith respect to the installation space. Thus, it is possible to disposethe totally enclosed main motor 5 of a high capacity. Meanwhile,comparison with an installation example of conventional main motors isgiven later in detail. The totally enclosed main motor 5 is installedunder the floor by, for example, suspending it using a suspendingdevice.

A shaft 6 that transmits the rotary drive force to the axle 3 a isattached at one end to the totally enclosed main motor 5 and isconnected at the other end to the axle 3 a. FIG. 3 is a detail viewillustrating a joint portion 12 between the axle 3 a and the shaft 6. Asillustrated in FIG. 3, a rectangle cardan system is used as an exemplaryconnecting method in the present embodiment. That is, the shaft 6 andthe axle 3 a are placed orthogonal to one another, and a gear 13attached to the tip of the shaft 6 engages with a gear 14 attached inthe central portion along the longitudinal direction of the axle 3 a.With this, the rotations of the shaft 6 are transformed into therotations of the axle 3 a. In the present embodiment, the drive force ofthe totally enclosed main motor 5 is directly transmitted only to theaxle 3 a, which is disposed at the near side of the totally enclosedmain motor 5 than the axle 3 b. That is, in the present embodiment, thetotally enclosed main motor 5 is coupled with only one of the two axlesthat are attached to the same chassis.

FIG. 4 is a cross-sectional view illustrating an exemplary configurationof the totally enclosed main motor 5. As essential constituent elementsof the totally enclosed main motor 5; a stator 51, a stator winding 52that is wound around the stator 51, and a rotor 53 are illustrated inFIG. 4 by the corresponding reference numerals. Moreover, as a coolingmechanism of the totally enclosed main motor 5, an inside airventilating flue 54 inside which the sealed air in the main motorcirculates and an outside air ventilating flue 55 through which theoutside air drawn in from a suction inlet 58 flows and then leaves froman exhaust outlet 59 are disposed. In addition, in the inside airventilating flue 54 is disposed an inner fan 56 that allows the insideair to circulate. Similarly, in the outside air ventilating flue 55 isdisposed an outer fan 57 that allows the outside air to let in from thesuction inlet 58.

Due to the operation of the totally enclosed main motor 5, heat isgenerated internally thereby causing a rise in the temperature of theair in the inside air ventilating flue 54. However, since the inside airhaving its temperature increased circulates in the inside airventilating flue 54, heat is released to the outside via a radiating finor the like. Moreover, since heat exchange occurs around the stator 51across the wall surfaces of the inside air ventilating flue 54 and theoutside air ventilating flue 55, heat is released to the outside alongwith the outside air flowing through the outside air ventilating flue55. Furthermore, since there is no direct air exchange between theinside air ventilating flue 54 and the outside air ventilating flue 55,even containing dust in the outside air, the dust is prevented fromentering into the inside of the main motor.

As illustrated in FIGS. 1 and 2, a ventilating duct 9 that is used todraw in the outside air is attached to the totally enclosed main motor5. The ventilating duct 9 opens toward the outside of the vehicle at theside covers 8. More particularly, the ventilating duct 9 has two openends, one open end being connected to the suction inlet 58 of thetotally enclosed main motor 5 and the other open end being guided to anopening 10 that is formed on the side covers 8. The other open end ofthe ventilating duct 9 and the opening 10 are mutually connected in amatching manner. In this way, in the present embodiment, the opening 10is formed on the side cover 8 that is disposed at one side of thevehicle and the ventilating duct 9 is disposed to connect the suctioninlet 58 to the opening 10. This makes it possible to supply the airfrom the outside of the vehicle directly to the outside air ventilatingflue 55. Meanwhile, the opening 10 is, for example, rectangular inshape.

In the totally enclosed main motor 5, the exhaust outlet 59 is placed onthe side at which the chassis 2 is connected to the totally enclosedmain motor 5 via the shaft 6; while the suction inlet 58 is placed onthe opposite side of the side at which the chassis 2 is connected to thetotally enclosed main motor 5 via the shaft 6. The ventilating duct 9elongates from the totally enclosed main motor 5 along the runningdirection of the vehicle, then bends in a substantial right angle, andlinearly elongates up to the opening 10 formed on one of the side covers8. Particularly, the ventilating duct 9 is so disposed that it liesperpendicular with respect to the side cover 8 at the opening 10.Meanwhile, in FIG. 2, the flow of the outside air is illustrated byarrows. The air from the outside of the vehicle is supplied to thetotally enclosed main motor 5 via the ventilating duct 9 and exhaustedfrom the totally enclosed main motor 5 to the side at which the chassis2 lies.

The connecting portion of the ventilating duct 9 with respect to thetotally enclosed main motor 5 is, for example, a connecting portion 11that has a bellows shape with retractility and flexibility. Even if thejoint portion between the totally enclosed main motor 5 and theventilating duct 9 is subjected to stress due to the vibrations ormovement generated along with the running of the vehicle, the connectingportion 11 elongates or contracts, or flexibly deforms along thelongitudinal direction of the vehicle and reduces the vibrations ormovement in a flexible manner. Therefore, the connection reliabilitybetween the totally enclosed main motor 5 and the ventilating duct 9 issecured in a stable manner.

Meanwhile, it is desirable to dispose, for example, a dust collectingfilter 17 at the opening 10 such that it becomes possible to collect thedust contained in the air that flows in the ventilating duct 9 from theoutside of the side cover 8. Thus, the dust can be prevented fromentering into the ventilating duct 9 and the outside air ventilatingflue 55. The dust collecting filter 17 can be disposed at the opening 10or at the open end of the ventilating duct 9.

Given below is the description with reference to FIGS. 1 to 4 of thebehavior of the abovementioned configuration according to the presentembodiment. Due to the operation of the totally enclosed main motor 5,heat is generated therein. The generated heat causes a rise in thetemperature of the sealed air in the inside air ventilating flue 54. Themovement of the inner fan 56 allows the air having its temperatureraised to circulate in the inside air ventilating flue 54. Meanwhile,since the outside air ventilating flue 55 is communicated with theventilating duct 9 and since one end of the ventilating duct 9 openstoward the outside of the vehicle at the opening 10, the air of arelatively low temperature is drawn in from the outside of the vehicleto the outside air ventilating flue 55 by the operation of the outer fan57. The drawn-in air of a relatively low temperature then flows throughthe outside air ventilating flue 55. Subsequently, heat exchange occursbetween the high temperature air circulating in the inside airventilating flue 54 and the relatively low temperature air flowingthrough the outside air ventilating flue 55. As a result, heat isreleased to the outside.

Given below is the effect of the present embodiment. According to thepresent embodiment, since the ventilating duct 9 is disposed to connectthe suction inlet 58 of the totally enclosed main motor 5 to the opening10 that is provided on one of the side covers 8, the air of a relativelylow temperature is constantly supplied from the outside of the vehicleto the outside air ventilating flue 55. That enables achievingenhancement in the cooling efficiency of the totally enclosed main motor5.

Given below is the description with reference to FIGS. 8 and 9 about acase when the ventilating duct 9 is not disposed. FIG. 8 is a schematicside view illustrating a configuration of a vehicle driving apparatusthat does not include a ventilating duct. FIG. 9 is a schematic planview illustrating the configuration of the vehicle driving apparatusillustrated in FIG. 8 when the bottom part of the corresponding vehicleis viewed from below. Herein, the constituent elements identical tothose illustrated in FIGS. 1 and 2 are referred to by the same referencenumerals.

With reference to FIGS. 8 and 9, the totally enclosed main motor 5 drawsin the outside air around the installation location from the suctioninlet 58 and then exhausts high temperature air having a highertemperature than the temperature at the time of drawing in the outsideair. Since the side covers 8 are disposed at the underfloor sides of thevehicle body 1, the high temperature air expelled by the totallyenclosed main motor 5 tends to stagnate in the region surrounded by theside covers 8. Because of this, the totally enclosed main motor 5happens to draw in the high temperature air from around the installationlocation and guide the drawn-in air in the outside air ventilating flue55. As the totally enclosed main motor 5 carries on with the operation,the difference in the temperature of the air flowing through the outsideair ventilating flue 55 and the temperature of the air circulating inthe inside air ventilating flue 54 becomes gradually smaller. Thiscauses substantial degradation in the cooling efficiency of the electricmotor. In comparison, in the present embodiment, the outside air fromthe outside of the vehicle is reliably supplied via the ventilating duct9 as the cooling wind that is not affected by the exhaust heat from thetotally enclosed main motor 5. This enables achieving a high coolingefficiency.

Moreover, in the present embodiment, by drawing in the air with theoperation of the outer fan 57, the cooling wind from the outside of thevehicle is supplied to the totally enclosed main motor 5 via theventilating duct 9. That is, the outside air is drawn in by effectivelyutilizing the already-established features of the totally enclosed mainmotor 5. This eliminates the need of newly disposing a device forproducing a forced ventilation. Furthermore, for example, a vehicle heattransfer apparatus disclosed in Patent Literature 2 utilizes the vehiclerunning wind generated when the vehicle is running as the cooling wind.In contrast, in the present embodiment, the air can be drawn in by usingthe outer fan 57 even if it is not possible to obtain sufficient vehiclerunning wind when the vehicle slows down or when the main motor isoperating after the vehicle comes to a halt. Thus, it becomes possibleto maintain a high cooling efficiency. Meanwhile, the object of PatentLiterature 2 is to perform cooling of an electric equipment such as atransformer or a reactor. This object is different from the object ofthe present embodiment, which is to perform cooling of a totallyenclosed main motor.

In the present embodiment, the suction inlet 58 and the exhaust outlet59 provided on the totally enclosed main motor 5 are sufficiently spacedapart. More particularly, the exhaust outlet 59 is placed on the side atwhich the chassis 2 is connected to the totally enclosed main motor 5;while the suction inlet 58 is placed on the opposite side of the side atwhich the chassis 2 is connected to the totally enclosed main motor 5.Since the inlet side and the exhaust side are sufficiently spaced apart,the inlet side is not easily affected by the heat of the exhaust air.That contributes in enhancing the cooling efficiency. Moreover, such anarrangement also facilitates easy installation of the ventilating duct9.

In the present embodiment, the ventilating duct 9 lies perpendicularwith respect to the side covers 8 at the opening 10. Consequently, theair entering into the ventilating duct 9 from the opening 10 flowsperpendicular with respect to the side covers 8. Such a configuration isfeasible because of the abovementioned feature of drawing in the coolingwind without having to use the vehicle running wind. Thus, unlike in thecase of having to use the vehicle running wind, there is no need todispose the ventilating duct 9 at a slant with respect to the side cover8. This makes the configuration simpler and installation easier.Moreover, the length of the ventilating duct 9 also decreases therebyenabling achieving cost reduction. However, identical to theconventional configuration, it is of course possible to dispose theventilating duct 9 at a slant with respect to the side covers 8.

Since the dust collecting filter 17 is disposed at the opening 10, thedust contained in the air from the outside of the vehicle is preventedfrom entering into the ventilating duct 9. Consequently, the outside airventilating flue 55 is also saved from the problem of the dust enteringtherein. This makes it easier to perform maintenance of the totallyenclosed main motor 5.

Moreover, since the connecting portion 11 provided between the suctioninlet 58 and the ventilating duct 9 has retractility and flexibility, itis possible to absorb the vibrations or movement generated along withthe running of the vehicle. That enhances the connection reliabilitybetween the totally enclosed main motor 5 and the ventilating duct 9.

Furthermore, according to the present embodiment, the totally enclosedmain motor 5 is disposed outside the frame of the chassis 2. Thiseliminates the dimensional constraints regulated by the chassis 2 whileinstalling the totally enclosed main motor 5. Thus, it is possible todispose the totally enclosed main motor 5 of a high capacity. That is,by loading the totally enclosed main motor 5 to the vehicle body portionother than the chassis 2, it becomes possible to secure sufficient spaceand thus increase the capacity of the totally enclosed main motor 5.

Given below is the description with reference to FIG. 10 of an exemplaryconfiguration in which main motors are disposed on a chassis. FIG. 10 isa plan view illustrating a configuration of a conventional vehicledriving apparatus. In FIG. 10, main motors 101 a and 101 b are disposedin a diagonal manner on a chassis frame 104. On the chassis frame 104are disposed axles 105 a and 105 b. A wheel 106 is impactedly fixed toboth ends of each of the axles 105 a and 105 b. A gear device 102 a isconnected to the axle 105 a, while a gear device 102 b is connected tothe axle 105 b. The rotating shaft of the main motor 101 a and thepinion shaft of the gear device 102 a are flexibly coupled by agear-type flexible coupling 103 a. Similarly, the rotating shaft of themain motor 101 b and the pinion shaft of the gear device 102 b areflexibly coupled by a gear-type flexible coupling 103 b. The rotatingshafts of the main motors 101 a and 101 b lie parallel to the axles 105a and 105 b.

In such a conventional vehicle driving apparatus, it can be seen thatthe dimensions of the main motors 101 a and 101 b are constrained by thechassis frame. That is, it can be seen that the dimensional constraintsby the rail width and the constraints by a distance 300 between the axleand the gear pinion (center distance) make it difficult to dispose mainmotors of a high capacity.

In the present embodiment, if the totally enclosed main motor 5 were tobe, for example, an induction motor; then it was found that the capacityof the totally enclosed main motor 5 can be enhanced up to about twicethe conventional capacity. Thus, unlike the example in FIG. 10 in whichtwo main motors 101 a and 101 b are disposed with respect to the samechassis frame 104; a single totally enclosed main motor 5 is disposedwith respect to a single chassis 2. This enables achieving substantialenhancement in the cooling efficiency while maintaining the runningperformance as before.

Since the totally enclosed main motor 5 is disposed outside the frame ofthe chassis 2, the shaft 6 is disposed to connect the totally enclosedmain motor 5 to the axle 3 a. In addition to its primary function oftransmitting the rotary drive force of the totally enclosed main motor 5to the axle 3 a, the shaft 6 has good heat conductivity because of itsmetallic material. Thus, by helping the heat to release from the totallyenclosed main motor 5, the shaft 6 contributes to the cooling effect.This enables achieving enhancement in the cooling efficiency of thetotally enclosed main motor 5.

As described above, according to the present embodiment, in addition toachieving less maintenance and low noise, it is possible to provide avehicle driving apparatus that includes the totally enclosed main motor5 having a high capacity and enhanced cooling efficiency.

Second Embodiment

FIG. 5 is a schematic plan view illustrating a configuration of thevehicle driving apparatus according to the present embodiment when thebottom part of the corresponding vehicle is viewed from below. In thepresent embodiment, the structure of a ventilating duct 19 is differentfrom the structure of the ventilating duct 9 in the first embodiment.Meanwhile, in FIG. 5, the constituent elements identical to thoseillustrated in FIG. 2 are referred to by the same reference numerals andthe detailed description thereof is omitted.

As illustrated in FIG. 5, the ventilating duct 19 is a T-shaped ducthaving three open ends. One of the three open ends is connected to thesuction inlet 58 of the totally enclosed main motor 5. One of theremaining two open ends is connected to an opening 18 a that is formedon the side covers 8 disposed at one side of the vehicle, while theother of the remaining two open ends is connected to an opening 18 bthat is formed on the side covers 8 disposed at the other side of thevehicle. In this way, in the present embodiment, the openings 18 a and18 b are formed on the side covers 8 that are disposed at the mutuallyopposite sides. Moreover, a dust collecting filter 20 a is disposed atthe opening 18 a and a dust collecting filter 20 b is disposed at theopening 18 b.

According to the present embodiment, for example, even if the opening 18a formed on one of the side covers 8 gets clogged due to foreignparticles, it is possible to use the other opening 18 b to draw in theair from the outside of the vehicle. Thus, it becomes possible to obtaina stable flow of the cooling wind through the ventilating duct 19.Meanwhile, although two openings are formed on the side covers accordingto the present embodiment, the number of openings is not limited to twoand it is generally possible to form more than two openings. Apart fromthe above description, the configuration, the behavior, and the effectof the present embodiment are identical to that of the first embodiment.

Third Embodiment

FIG. 7 is a schematic plan view illustrating a configuration of thevehicle driving apparatus according to the present embodiment when thebottom part of the corresponding vehicle is viewed from below. FIG. 6 isa schematic plan view illustrating an exemplary modification of theconfiguration of the vehicle driving apparatus according to the presentembodiment when the bottom part of the corresponding vehicle is viewedfrom below. Meanwhile, in FIGS. 6 and 7, the constituent elementsidentical to those illustrated in FIG. 2 are referred to by the samereference numerals and the detailed description thereof is omitted.

As illustrated in FIG. 7, in the present embodiment, a ventilating duct30 for exhaust air is disposed in the configuration according to thesecond embodiment illustrated in FIG. 5. More particularly, one end ofthe ventilating duct 30 is connected to the exhaust outlet 59 of thetotally enclosed main motor 5 and the other end of the ventilating duct30 is connected to an opening 31 formed on the side covers 8.

Because of the ventilating duct 30 for exhaust air, the high temperatureair exhausted from the outside air ventilating flue 55 of the totallyenclosed main motor 5 can be reliable exhausted to the outside of thevehicle. That is, the air having its temperature increased due to therelease of heat in the totally enclosed main motor 5 does not stagnatearound the totally enclosed main motor 5. This enables achieving furtherenhancement in the cooling efficiency.

Moreover, in the totally enclosed main motor 5, the suction inlet 58 andthe exhaust outlet 59 are sufficiently spaced apart. Particularly, theexhaust outlet 59 is placed on the side of the chassis 2 to which thetotally enclosed main motor 5 is connected, while the suction inlet 58is placed on the opposite side of the chassis 2 to which the totallyenclosed main motor 5 is connected. The ventilating duct 30 for exhaustair is connected to the exhaust outlet 59. The ventilating duct 30elongates along the connecting direction, then bends in a right anglewith respect to the running direction of the vehicle, and connects tothe opening 31 formed on the side covers 8. Therefore, the position ofthe opening 31 used in exhaust air is sufficiently spaced apart from thepositions of the openings 18 a and 18 b used in suction air. Thus, theinlet side is not easily affected by the heat of the exhaust air.

Meanwhile, the exhaust air via the ventilating duct 30 is performed bythe operation of the outer fan 57 that is disposed in the outside airventilating flue 55 of the totally enclosed main motor 5. Thiseliminates the need of newly disposing a device for producing a forcedblast. Moreover, there is also no need of using the vehicle running windas is the case in the conventional technology.

The shape of the ventilating duct 30 for exhaust air is not limited tothe shape according to the present embodiment and can be configured in,for example, T shape that is identical to the ventilating duct 19 usedin suction air. Moreover, the connecting portion of the ventilating duct30 with respect to the totally enclosed main motor 5 can be configuredto have retractility and flexibility in an identical manner to theconnecting portion 11. Apart from the above description, theconfiguration, the behavior, and the effect of the present embodimentare identical to that of the second embodiment.

Given below is the description with reference to FIG. 6 of an exemplarymodification of the present embodiment. As illustrated in FIG. 6, in thepresent modification, the ventilating duct 19 used in suction air isremoved from the configuration illustrated in FIG. 7. That is, regardingsuction air, the air surrounding the suction inlet 58 is utilized. Then,by discharging the high temperature air that has been exhausted from theexhaust outlet 59 to the outside of the vehicle in a reliable manner,the rise in temperature around the suction inlet 58 is curbed as ameasure to enhance cooling efficiency of the totally enclosed main motor5. Thus, the third embodiment has a combined effect of the secondembodiment and the present modification.

INDUSTRIAL APPLICABILITY

In this way, the present invention is suitable in a high-speed vehiclein which side covers are disposed at the sides of the bottom part of thevehicle.

1. A vehicle driving apparatus that is disposed in a vehicle having aside cover at an underfloor side of a vehicle body and that runs thevehicle, with an electric motor as a power source, by rotatively drivingan axle disposed on a chassis of the vehicle and a wheel fixed to theaxle, the vehicle driving apparatus comprising: a totally enclosedelectric motor that is disposed outside a frame of the chassis placedunder a floor of the vehicle body, that includes an outside airventilating flue through which outside air is suctioned from a suctioninlet, circulated and exhausted from an exhaust outlet, and that usesthe outside air ventilating flue to release heat generated internally tooutside; a shaft that transmits a rotary drive force of the totallyenclosed electric motor to the axle; and a ventilating duct thatconnects between the suction inlet and an opening formed on the sidecover.
 2. The vehicle driving apparatus according to claim 1, whereinthe suction inlet of the totally enclosed electric motor is disposed onan opposite side of the chassis to which the totally enclosed electricmotor is connected, and the exhaust outlet of the totally enclosedelectric motor is disposed on a side of the chassis to which the totallyenclosed electric motor is connected.
 3. The vehicle driving apparatusaccording to claim 2, wherein, the ventilating duct is disposed so as tobe perpendicular to the side cover at the opening.
 4. The vehicledriving apparatus according to claim 3, wherein the ventilating duct hasT shape with a first open end, a second open end, and a third open end,the first open end being connected to the suction inlet, the second openend being connected to an opening formed on the side cover disposed atone side of the vehicle, and the third open end being connected to anopening formed on the side cover disposed at the other side opposite tothe one side of the vehicle.
 5. The vehicle driving apparatus accordingto claim 1, wherein a dust collecting filter is provided at the opening.6. The vehicle driving apparatus according to claim 2, wherein a dustcollecting filter is provided at the opening.
 7. The vehicle drivingapparatus according to claim 3, wherein a dust collecting filter isprovided at the opening.
 8. The vehicle driving apparatus according toclaim 4, wherein a dust collecting filter is provided at the opening.